


a mirror with no one inside

by billbert



Category: It's Always Sunny in Philadelphia
Genre: Anal Sex, Angst and Hurt/Comfort, Blow Jobs, First Kiss, First Time, M/M, Unrequited Love, dennis is so dramatic and mac is so smitten, mac fucks dennis
Language: English
Status: Completed
Published: 2020-03-01
Updated: 2020-03-01
Packaged: 2021-02-19 07:36:05
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,800
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22974226
Author URL: https://archiveofourown.org/users/billbert/pseuds/billbert
Summary: dennis fucks mac for validation.
Relationships: Mac McDonald/Dennis Reynolds
Comments: 19
Kudos: 125





	a mirror with no one inside

**Author's Note:**

> my first time writing these two and god DAMN it was intense. what a ride! pls enjoy!

"Dude, are you drunk? Are you okay?" Mac asked as Dennis walked in, stumbling over his feet, face flushed. Usually, Dennis was good at holding his alcohol, but apparently not tonight. He looked awful, dark circles under his eyes, the purple standing out against his pale skin - and yet, Mac still thought he was the prettiest thing in the world.

"I'm not fucking drunk. I'm just _upset._ Leave me alone-" Dennis scoffed, lurching forward in the direction of his bedroom. Mac's heart cracked, he wanted so badly to soothe Dennis, but after 15 years of friendship, he knew that might be impossible. Still, he made his way forward, wrapping his arms around his best friend, who stood straight, arms at his sides. Dennis had never been one for hugs.

"Get off me, I need to be alone-" Dennis begged weakly, struggling like a wet noodle against Mac's warm grip. Mac conceded, taking a step back. He pouted in spite of himself - but now wasn't the time to focus on his own feelings. He needed to make sure Dennis was okay. He was less and less okay as the years went on, no matter what Mac did, no matter how much he reached out.

"If that's what you want- but I really think you should talk to me first." Mac said plainly, looking Dennis right in the eyes. His hair was all over the place, his gaze was cold and sad and lonely. Or at least, that's what Mac saw. Maybe that was all he wanted to see. 

"Fine, we can talk for a little bit. What the fuck do you want? I'll talk. I'll talk about whatever the hell you want, 'cause I'm such a good _friend._ Just tell me what you want so I can go in my fucking room." Dennis snapped, and Mac winced at the venom in his tone. Why couldn't he help? Was there no helping someone who was so far gone? It may be futile, but Mac would keep trying until the planet exploded.

"I...I don't _want_ anything, I just think you shouldn't be alone right now - not if you're feeling so bad." Mac stated simply. He knew Dennis had a self-destructive streak, and when he was like this there was no telling what he might do if left alone. Despite pushing thirty, Dennis was still wont to harm himself in ways one might've associated with teenagers.

"Fine. But I need to lay down, so let's...let's at least go into my room, alright?" Dennis sighed, straightening himself out and taking a few deep breaths. Mac was just glad he didn't start yelling. He hated it when Dennis yelled at him, it made him feel like a kid again, that feeling of smallness, of helplessness.

"Sure." Mac grinned, wrapping his arm around Dennis and leading him into his bedroom. His heart was beating harder just from that contact alone, and he cursed it. He cursed it and cursed it and cursed it, but it would happen every single time he got close to Dennis and he was used to it. All along, Mac had wished he and Dennis were fire and ice, that he'd slowly melt and show his true colors, but Dennis was marble and Mac couldn't do anything about that.

"I just can't handle it anymore." Dennis said under his breath, a shaky little statement that held a bit of the vulnerability Mac so desperately desired. Maybe he was selfish, maybe he was disgusting for the way his mind wandered when he was supposed to be helping his friend. He tried sweeping the thoughts away as though with an imaginary broom, but they stuck to the linoleum and melted into it forevermore.

Dennis flopped on the bed the second they entered the room, peeling himself away from Mac's grasp as always. He was on his back, staring up at the ceiling with blank eyes that held the world in them. Mac sat on the edge of the bed, his thigh touching Dennis' leg. He had to keep that contact, he was needy, he was desperate.

"So...what's wrong, exactly?" Mac ventured, glancing back at Dennis, who was unresponsive. He responded with a simple shake of the head, shutting his eyes. Mac breathed in deeply, loving the way the room smelled like him. He wanted so badly to help, but he knew that he couldn't. Dennis' problems would always be bigger than him, the same way his presence was, the same way his talents were - Dennis was always better and bigger and Mac knew he didn't deserve him.

"If you don't want to talk about it, that's okay-" Mac said quietly. "We can just lay here." He offered, flopping backward next to Dennis. He turned his head, admiring the way Dennis' curls spread out ever so slightly against the blankets. He studied his features intently, the way he always did. He'd held on for too long and there was no letting go now.

To his surprise, Dennis sat up. He was trembling and Mac's heart shattered a little at that. He never wanted him to hurt, but he knew that Dennis' insides were black and venomous and he should probably stay far, far away. "I don't need to talk. Sit up." Dennis said softly, though there was still bile in his tone.

"What do you need?"

"Call me pretty-?" Dennis asked, voice smaller and weaker than usual. Mac instantly sat up beside him, ready to heap compliments on him. Dennis needed that sometimes, and Mac was all too happy to spill his feelings, ready to open his heart up and pour his affection all over Dennis, let it fill up the cracks in his ego.

"You know you're beautiful," Mac said, leaning in and stroking Dennis' cheek, anticipating his hand being swatted away. Dennis let the hand stay there. He shut his eyes, lashes fluttering as he took deep breaths. "The prettiest person I know. I'll always think so." Dennis smiled a little at that, a tiny laugh escaping his lips. Mac wished he could kiss him.

"I know, I know-" Dennis smirked, some of his usual personality fading back into his voice. As much as Mac loved seeing Dennis' rare vulnerable side, he preferred him happy. "Get a little more specific." 

Mac was all too happy to. "Your hair is so gorgeous-" He sighed, running a hand through it. "So are your eyes- I could stare into them forever. Your lips, too. I can't stop looking at them." Mac gushed, knowing his words would be met with sarcasm and laughter and he didn't care. Dennis knew all too well how Mac felt about him, and Mac was unfortunately all too content being his little compliment dispenser.

"What about my body?" Dennis asked, cocking his head. Clearly, someone had rejected him today. He always got like this after rejection - though how someone could reject Dennis, Mac had no idea. He was a spider and Mac would forever be twisting around in his webs until the day he got swallowed whole.

"Your body is perfect," Mac said simply. "Why are you even asking? You know that. Are you sure you don't want to talk about what happened?"

"No, I don't. Just keep touching me-" Dennis sighed, eyes still shut. Mac raised his eyebrows - that was a new one. He continued stroking Dennis' hair until Dennis grabbed his wrist and moved his hand lower until it was pressed flat against his chest. "Touch me like you love me." He practically begged, clearly needing a lot more validation than Mac was providing.

Mac's face instantly heated up at that, and he sucked in a long breath through his nose, eyes widening. "You...want me to touch you?" He asked shyly, suddenly a little overwhelmed. "Like, I...fuck, you know I might not be able to hold back-" He barely managed to get the words out, they were caught in his throat and he was fighting back so many feelings for Dennis' sake, always for Dennis, _always for Dennis..._

"You heard me. If you can't do it, I'll show you." Dennis snapped, a bit of bite finally coming back into his tone. He swung a leg over Mac's lap, straddling him. Mac looked up into his face, completely dumbfounded. Suddenly, he didn't know what to do. He'd never gotten this far with Dennis before, not ever. He was panting and desperate and red and that was only after a few seconds of contact. He'd wanted this for a decade and now he had no idea what to do with himself.

Thankfully, Dennis suddenly took the lead, pressing a kiss to Mac's lips out of nowhere. Mac's body and mind both short-circuited, filled with a fire so hot it almost felt cold - goosebumps everywhere. He'd always heard of how kissing could feel like fireworks, but he'd never believed it until now. 

As soon as he regained control of his limbs, he wrapped them around Dennis, tugging him closer hungrily. He kissed with fervor, trying to pour as much of his feelings into the kiss as he could. He was already half-hard, and he was positive Dennis could feel it. He cursed himself for being so eager, but there was no way he could remain calm - not like this.

Dennis' tongue slid between his lips, taking Mac by surprise. But he wasn't complaining in the slightest. He slid a hand lower, resting it on the small of Dennis' back as the other hand carded through his curls. Dennis moaned a little in affirmation, and Mac wanted to cry. For so long, for so _so_ long he'd wanted that. The reasons Dennis was doing this didn't matter. Nothing mattered except kissing and touching and _fuck-_

Dennis pulled away with a small smile tugging up the corners of his mouth. "You want me that bad?" He chuckled, very little sincerity in his voice. Mac didn't care. This was _exactly_ what he wanted and he wasn't about to let it slip away for dumb reasons like _Dennis is just using you for validation and nothing else._

Mac let out an involuntary gasp as Dennis rolled his hips down with an evil grin. "You love this, huh?" He sneered, clearly in a better mood than he'd been ten minutes ago. Mac was always happy to help, especially if the benefits were _this_ good. "You idiot- you love this-" Dennis panted, grinding against him with enthusiasm. "Want me so bad-"

Mac nodded enthusiastically. He _did_ want him so bad, wanted him more than anything in the universe. "I love it, I love it-" He managed, though it was hard to cough the words up with Dennis moving against him like that. Dennis had a really cocky smirk on his face, looking down on Mac, clearly getting off on the sense of power. Mac didn't care.

"So stupid- so precious-" Dennis cooed, a finger tracing down Mac's jawline. "You belong to me, huh?" Mac nodded and nodded until he felt like a bobblehead. Dennis chuckled, sliding off of his best friend's lap and taking a place between his legs on the floor. Mac's eyes widened. He wasn't sure if this was a good idea at _all,_ but his dick was in full control and there was no stopping what had already been started.

"Look at you-" Dennis smiled, eyes curving up mischievously. "So desperate...just from seeing me on the floor like this. This'll only happen once, so enjoy it, alright?" He rambled, and Mac noticed that he was still trembling a little. Though his walls were back up, they were paper-thin and Mac saw that Dennis was just as vulnerable as he'd been before. He probably shouldn't take advantage of the situation, lest Dennis regret it tomorrow, but his hands were already undoing his pants, sliding them down, freeing his cock, fuck- it was so fast. He couldn't refuse.

_It was all happening too fast._

"So hard for me-" Dennis grinned, wrapping a hand around the base of Mac's cock, stroking it slowly, nuzzling his face against it like a slut. Mac couldn't handle the image, he was already close just from _seeing_ that. Dennis paused for a moment and Mac was terrified he'd walk out, but instead, he just locked eyes with him, hand stilling. "Say something-"

Oh. Shit. That's right, this was all about validation, he had to help Dennis, had to make him feel perfect and special and pretty like he always did-

"You look beautiful down there-" Mac managed. Dennis clearly wanted more, but he began to move his hand again, smiling up at Mac coyly as if daring him to continue. "This- fuck, this is what I've always wanted-"

"How many times have you imagined this?" Dennis asked softly, tongue poking out for a moment, circling the tip. Mac couldn't help but moan at that, hand reaching out to run through Dennis' hair, urging him just a little closer. He couldn't handle it, and knowing it was the one and only time he'd experience this was about to break him into a million little pieces.

"So many times, fuck- _so many times_ -" Mac blabbered, mouth hanging open like a fish as he watched Dennis shut his eyes, lean forward, start to take it in- oh _fuck_. It felt amazing, Mac couldn't help but wonder if Dennis had done this before. He wanted to wring the necks of the bastards who'd had the privilege of experiencing this before him.

"Mmm-" Dennis moaned softly, bobbing his head back and forth as his thin hand worked the base. Mac was using every little ounce of strength he had left to prevent himself from cumming too soon, but he knew he only had about thirty seconds left. Dennis just looked so _perfect_ between his legs, stray curls flopping into his face as he moved.

"Fuck, Den- I can't, I can't, you're gonna make me- _fuck_ , that's so good-" Mac spluttered, voice raspy and desperate with arousal. Dennis pulled off, hand still working fervently. There was a peculiar shine in his eyes, an eagerness to please that Mac had never seen before. It suited him, made the usually cold man look...sort of _cute._

_He's so perfect._

"Go ahead-" Dennis smiled deviously, leaning forward to lick at the tip again. Mac grabbed him by the hair and made him take it again - Dennis would probably chastise him for that later, but Mac knew this was his one and only chance, so he wanted to enjoy it. To control Dennis for a second, rather than being dragged about as always.

He lasted a couple more seconds, pushing Dennis down further until he couldn't hold on anymore, spilling himself down that tight throat. "Fuck, I love you- _I love you so much_ -" He blurted as he came, wishing he could make eye contact. But Dennis' eyes were closed, and his ears must've been closed too, because he didn't react. Perhaps it was because he already knew. 

Dennis pulled away slowly, making a big show of swallowing. Mac stared at him with wide eyes, still barely believing this was reality. "Fuck, Den, that was perfect- so perfect-" 

"We're not done yet." Dennis smirked, wiping his mouth on the back of his hand. He stood up slowly, clearly enjoying how Mac's eyes were glued to him. His walls were no longer thin and able to be torn through, they were made of concrete and impossible to penetrate. Mac bit his lip and blinked away tears. Even though he should've been overjoyed, he felt his insides twisting up in pain as Dennis slowly removed his own clothes.

He didn't have anything left to say, his mouth dry and head both full to bursting and completely empty at the same time. Dennis was in his underwear, slowly approaching him - Mac didn't need to be seduced. He was already as far gone as a person could get, so deeply in love that it was suffocating and frustrating and _upsetting._

_It's okay if he uses me. As long as I can be next to him-_

Dennis' spindly hands pressed against his shoulders and pushed him back against the mattress. Mac just went with it, limp like a paper doll. He couldn't move, couldn't think, all he could do was admire. Dennis clearly wasn't satisfied with that, though. He frowned at Mac as he climbed on top of him.

Mac shut his eyes and saw something he didn't want to remember.

_"Dennis, stop! You're getting too high- gimme the joint-" Charlie yelled, snatching it out of his hand. Mac grinned as Dennis rested his head on his shoulder. The contact made him buzz with happiness. Charlie looked around to make sure no teachers were around before taking a long drag._

_"You're right, I'm too high." Dennis laughed, scooting closer to Mac until their bodies were pressed against each other. "I love you guys, I really do-"_

_"Fuck, you smoked like, half of it! You'd never say that shit otherwise. You greedy fuck!" Charlie complained. Mac didn't care. He had more, they could always roll another. He'd give up all his weed if it meant he and Dennis could stay like this for just a bit longer. "You idiot. Look at you and Mac. You guys are totally out of it."_

_Mac wasn't out of it at all._

_"Mac, buddy-" Dennis said softly, looking up at him affectionately. "Mac, I fuckin' love you. You're the best. This is good shit - after school today, let's go over to my place and smoke some more." Mac nodded enthusiastically. Dennis grinned - a genuine smile. It melted Mac's heart. He couldn't believe he'd lucked out enough to get Dennis fucking Reynolds to be friends with him. To say he loved him._

Mac snapped out of it with a quick slap to the face. "You- are you even paying attention? I thought you wanted me-" Dennis growled, his eyes cold and completely unlike the way he'd looked at Mac in the memory. _I do want you,_ Mac thought desperately. _Just not like this._

"I'm sorry, I spaced out for a sec. This is all a lot-" Mac managed, reaching forward to grab Dennis by the hips, letting him know he was still into it. "But you know I want you. I want you so bad, it fucking hurts-" He groaned, watching as Dennis' face went from tense to relaxed again, watched as he reached down, working Mac's cock back to hardness.

Mac's breath hitched. It all got real for a second, too real. He was about to fuck Dennis Reynolds, and here he was, a puddle of emotion, unable to disconnect and just go with it. He just stared at him as he undressed, and despite being naked physically, Mac knew he'd never be able to lay his true feelings bare. Did he even _have_ feelings? Sometimes Mac wondered. How was it that he could use him this easily, lead him along like a dog? 

"Do you even know how this works?" Dennis glared, clearly not pleased with the lack of reaction. Suddenly, Mac was able to move again. He had to. And yeah, he knew how it worked. He was sick of Dennis trying to play him - it was time to show him how he _really_ felt. He sat up, shoving Dennis down on his back and positioning himself over him. Dennis seemed taken aback at the sudden display of aggression, though he didn't protest it. Quite the opposite, in fact.

_Was he blushing? Mac might've been imagining that part._

"Of course I fucking know how this works." Mac snapped, reaching over and fumbling around in Dennis' drawer. He knew he kept lube there from watching countless sex tapes. He knew this room like the back of his hand, but he couldn't say the same about Dennis. He waited with bated breath as he poured some of the lube on his fingers, spreading Dennis' legs roughly.

He wasn't going to be gentle, he knew that much. Dennis was just going to have to shut up and deal with it, the way Mac had been doing for ten fucking years. "I've never-" Dennis began, but quickly hushed up when Mac started pressing the first finger in. The tightness betrayed him - Mac would've never expected that Dennis hadn't done it with a guy before. But suffice to say he was happy, knowing that he'd be his first.

Dennis made a pained sound, head pressing back against the pillow as his back arched. "Shhh-" Mac urged him, working his finger inside until he was ready to take a second. He knew that it probably hurt, but fuck, it was nothing compared to the way Mac hurt. Every second of this, his heart was being stabbed. Over and over and over-

He _hated_ him.

"Mac, please-" Dennis whined as the second finger slowly made its way inside. "Please- please-" He begged uselessly. He was pink and panting and everything Mac had ever wanted. Mac urged his hand forward, curling his fingers upward - he knew what he was doing to an extent, it couldn't be that difficult to find -

 _"Fuck-! Mac- I need you-"_ Dennis suddenly yelped, wrapping his arms around Mac's shoulders, breathless and tense. "Fuck- It feels so good- more--" It was music to Mac's ears, and he couldn't help but lean down and press a kiss to Dennis' lips. It was gladly reciprocated, and Mac was on cloud nine, even though he knew this was just a charade, that Dennis didn't _actually_ give a shit.

The thought _really_ pissed him off. He removed the fingers harshly, resulting in a whimper from Dennis, who looked completely gone. It was pretty clear he'd never experienced any of this before, and he was out of his depth. It was a good look on him, clingy and desperate and _small._ Mac felt he had the power for the first time in their entire relationship.

He didn't ask for permission, just lubed his cock up and positioned himself against Dennis' entrance. Dennis waited with bated breath, silent except for that telltale quiet panting. He didn't resist, just stared up at Mac with an unreadable expression, pupils blown and lips parted. Mac shut his eyes, unable to handle how gorgeous that look was. He was swimming, his brain overwhelmed with thoughts as he slowly pressed himself inside.

_"Dude, I fucking hate you-" Dennis laughed, tossing his controller aside. That was the one thing Mac had over Dennis - he was fucking awesome at Super Smash Bros. He'd won five times and clearly Dennis was tired of being pummeled. "You're too fucking good at this, you asshole-" He complained, turning to face Mac._

_He was laughing. Mac loved it when he laughed. He sounded so pretty all the damn time, and it was overwhelming, to say the least. Mac wanted to kiss him so badly, but he held himself back the way he always would. He was nothing if not eager to please his new friend. Dennis was so perfect compared to the spotty, awkward mess that was Mac._

_He snapped out of his reverie. Dennis was staring at him, grinning stupidly. Mac felt his heart racing in his chest as Dennis reached forward, stroking Mac's cheek for a brief, wonderful moment. "Take this to your grave, but you've got pretty eyes, dude," Dennis remarked, before quickly retracting his hand and grabbing the controller. "I'll only say it once and it's only because you won, alright?"_

_Mac's heart couldn't handle it. It was a simple compliment, but it had been given to him by Dennis Reynolds of all people, who was still smiling like an idiot, clearly enjoying the lazy afternoon. He was beautiful and Mac hoped that someday Dennis would think the same of him, even if it was a pipe dream._

Mac came back to reality, looking down at Dennis, who was an absolute mess. He couldn't form words, that much was clear. Mac finally bottomed out, forcing Dennis' thin frame to take it. He felt overwhelmingly good, to the point where Mac couldn't hold back an ugly groan of pleasure.

"Fuck-" Dennis panted, arms around Mac's shoulders. "This- _fuck,_ I never thought this would feel so good-" Good might not've been the right word for it. Mac didn't think it was good, he thought it was perfect and terrible and _amazing_ and _regrettable._ He began to move, and though he didn't want to hurt Dennis, there was an angry energy in him that had been building up for 15 goddamn years, and it was all coming out right then and there.

He pounded into Dennis without much regard for the other's comfort, causing his best friend to let out a broken cry of pain and pleasure, head flopping back against the mattress. "Mac, fuck, slower-" He begged, but it only made Mac speed up. The fact that he was finally the one in control, that gave him such a rush that his rational thoughts were put on the back-burner.

He grabbed Dennis by the hips and really just had at it, trying to convey just how _frustrating_ this past decade and a half had been for him. He'd invested so much time and energy into Dennis, always what Dennis wanted, always what Dennis needed. He dug his nails into the pale, easily breakable skin and forced himself in over and over, loving the way Dennis' eyes practically rolled back into his head with each thrust.

He looked down at his angel, noticing something. Dennis was fucking _crying._ Whether it was from the pain or from the feelings, Mac didn't know. He reached down, slowing his pace a bit. He wiped away a tear, heart full of anger and sadness and fucking love. He was in love and he always would be, and it tore him apart. Seeing Dennis like this was making his own eyes well up, and he shut them in shame, tears splattering down onto Dennis' chest.

"Don't stop-" Dennis begged, voice shaky as he held back sobs. "Don't stop, I love you-" He whispered softly. Mac bit his lip, trying his best to retain some semblance of composure. Those words likely meant nothing, Dennis was probably just saying that so he'd stop crying and continue. But it still felt like an arrow to the heart, and Mac's tears fell harder and harder, light drizzles turning into a full-on storm.

_"I love you too, I love you so much-"_

It was too much. Mac couldn't handle the way Dennis was looking at him. He pulled out and flipped him over easily, quickly reminded of how much stronger he was compared to Dennis, who was pale and thin and angelic and perfect. Dennis shakily managed to position himself on his hands and knees, and Mac eagerly thrust back in, holding him still and fucking into him as hard as he possibly could.

He wouldn't last. He _couldn't_ last. He reached forward, roughly stroking Dennis' cock, resulting in a muffled moan. Dennis had buried his face in the pillow, body still trembling from arousal and sobbing. It wasn't long before Dennis came into his hand with a high-pitched cry, a sound Mac would store in his brain until the end of fucking time.

"I hate you, _I hate you_ -" Mac panted, feeling Dennis tighten around him. His hips had a mind of their own, and they snapped forward until he finally saw white, spilling himself deep inside Dennis, lazily riding out the orgasm. He knew this would be the last time, and he was loath to admit that. He so desperately wanted this to be the beginning of something new, but it was the end of something so, so old.

Slowly, he pulled out. Dennis collapsed onto his side, still crying like a baby. Mac's heart couldn't take it anymore. He crashed down next to him, turning over and spooning him like a lover would. Kissing his shoulders and neck, running his hand through his curls, trying his best to soothe him. He knew Dennis would never love him and that this whole thing was a mistake, a farce.

"Do you really hate me?" Dennis asked quietly.

"I should," Mac replied, touching him gently, turning him over so that they were face-to-face. "But I can't." He admitted, leaning in to kiss Dennis as chastely as possible post-sex. He really couldn't. There was a part of him that _wanted_ to hate Dennis, but he just couldn't. "I love you way too much."

"I love you too-" Dennis murmured, burying his face in the crook of Mac's neck. It made him cry, it made him weep, it made him break.

He broke and broke and broke and he never got past it.

Dennis was a dead end.

**Author's Note:**

> leave a comment if u can <3


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